Rails Datamapper (dm-rails) KeyError: key not found: "all"

I am using rails 3 with dm-rails gem.

Getting an error while searching for Model.all

adapter: Soap
  disable_format_extenstion_in_request_url: <%= ENV['xxxxxxxxx'].inspect %>
  format: <%= ENV['xxxxxxxxx'].inspect %>
  pub_key: <%= ENV['xxxxxxxxx'].inspect %>
  app_id: <%= ENV['xxxxxxxxx'].inspect %>
  institution_name: <%= ENV['xxxxxxxxx'].inspect %>
  ssl_keystore_file: <%= ENV['xxxxxxxxx'].inspect %>
  ssl_keystore_password: <%= ENV['xxxxxxxxx'].inspect %>
  wsdl_store: <%= ENV['xxxxxxxxx'].inspect %>

Any help on this? Thanks in advance.